1. Field of the Invention
The present invention relates generally to battery powered devices and, more particularly, to the detection and identification of performance components of a battery pack installed in such devices.
2. Related Art
Sudden cardiac arrest, i.e., a heart attack, has been attributed to over 350,000 deaths each year in the United States, making it one of the country's leading medical emergencies. Worldwide, sudden cardiac arrest has been attributed to a much larger number of deaths each year. One of the most common, and life threatening, consequences of a heart attack is the development a cardiac arrhythmia commonly referred to as ventricular fibrillation. When in ventricular fibrillation the heart muscle is unable to pump a sufficient volume of blood to the body and, more importantly, to the brain. Ventricular fibrillation is generally identifiable by the victim's immediate loss of pulse, loss of consciousness and a cessation of breathing. The lack of blood and oxygen to the brain may result in brain damage, paralysis or death to the victim.
The probability of surviving a heart attack or other serious heart arrhythmia depends on the speed with which effective medical treatment is provided. There are four critical components of effective medical treatment that must be administered to a victim of sudden cardiac arrest: (1) early cardiopulmonary resuscitation to keep the blood oxygenated and flowing to the victim's brain and other vital organs; (2) early access to emergency care; (3) early cardiac defibrillation to restore the heart's regular rhythm; and (4) early access to advanced medical care. If prompt cardiopulmonary resuscitation is followed by defibrillation within approximately four minutes of the onset of symptoms, the victim's chances of surviving sudden cardiac arrest can approach or exceed forty percent. Prompt administration of defibrillation within the first critical minutes is considered one of the most important components of emergency medical treatment for preventing death from sudden cardiac arrest.
Cardiac defibrillation is an electric shock that is used to arrest the chaotic cardiac contractions that occur during ventricular fibrillation and to restore a normal cardiac rhythm. To administer this electrical shock to the heart, defibrillator pads are placed on the victim's chest, and an electrical impulse of the proper size and shape is administered to the victim in the form of an electric shock. While defibrillators have been known for years, they have typically been large and expensive making them unsuitable for use outside of a hospital or medical facility.
More recently however, portable external defibrillators for use by first responders have been developed. A portable defibrillator allows proper medical care to be given to a victim earlier than preceding defibrillators, increasing the likelihood of survival. Such portable defibrillators may be brought to or stored in an accessible location at a business, home, aircraft or the like, ready for use by first responders. With recent advances in technology, even a minimally trained individual can operate conventional portable defibrillators to aid a heart attack victim in the critical first few minutes subsequent to onset of sudden cardiac arrest.
Portable defibrillators require a portable energy source to operate in the anticipated mobile environment. Several manufacturers have provided customized battery packs for their defibrillators. However, some portable defibrillators use a standard, commonly available, rechargeable battery pack, such as those used in video camcorders. Such battery packs are generally referred to herein as industry standard battery packs. The use of industry standard battery packs allows for a less expensive battery solution. These battery packs, while often having a standard mechanical and electrical interface, are available with different chemistries, such as lead acid, nickel cadmium, lithium or the like.
Certain battery-powered devices operate in accordance with certain modes of operation that place severe or otherwise specialized performance requirements on the power source. Such power source requirements must be supported by the installed battery pack for the device to operate in accordance with such operational modes when an alternating current power source is unavailable. However, industry standard battery packs are manufactured to support a wide range of battery-powered devices and, therefore, generally cannot support such specialized power source requirements. In addition to battery cells, battery packs include performance components that contribute to the ability of the battery pack to support such power source requirements. Performance components may be, for example, a thermal fuse, thermostat and current fuse.
Due to the inability of industry standard battery packs to meet a wide range of power source requirements, many device manufacturers also manufacture customized battery packs to support the specialized functions performed by the battery-powered device. Customized battery packs often have a performance component configuration that enables them to meet certain specialized power source requirements associated with certain devices or certain operational modes of a device.
Customized battery packs are, however, more expensive and less readily available than industry standard battery packs. As a result, rather than incurring the costs associated with the manufacture and use of such battery packs, many manufacturers limit the battery-powered device to those operations having associated power source requirements that can be adequately supported by industry standard battery packs. This, however, often results in the battery-powered device being configured to operate in modes which are not sufficient or at least not optimal for a given need of the device. In other words, the maximum performance of the battery-powered device is sacrificed for implementing a device that operates with industry standard battery packs.
An example of battery powered devices with specialized power source requirements are automatic external defibrillators (AEDs). Some of today's AEDs use industry standard camcorder sealed lead acid (SLA) battery packs such as the model LC-TA122P sealed lead acid battery pack available from Panasonic, Inc. AEDs require a large transfer of current in a short period of time when charging the energy delivery circuit. This places significant power source requirements on the installed battery pack. Such power source requirements generally cannot be satisfied by industry standard SLAs. As a result, rather than manufacturing customized battery packs that meet such specialized power source requirements, some AED manufacturers extend the time to charge the energy delivery circuit. There are drawbacks to this approach, however. Oftentimes, successful resuscitation of a defibrillating victim requires application of multiple defibrillation shocks. An increase in the time to charge the energy delivery circuit results in a corresponding increase in the time taken to deliver patient therapy.
What is needed, therefore is a technique for detecting performance components of battery packs. There is also a need for battery-powered devices that can modify the operational mode of the device based on the performance features that are provided in an installed battery pack.